As is known in the art, there are many diverse applications wherein materials are to be mixed, tumbled and/or blended. Similarly, there are many manufacturing processes which require the cleaning or shake-out of parts such as castings, moldings or bulk material, with or without a working media. For both types of applications, it is useful to utilize a tumbling apparatus to achieve the intended objective.
Some time ago, it was found that an improved finish could be obtained on cast or molded parts by adding a vibratory motion to a tumbling apparatus. For instance, in my earlier U.S. Pat. No. 3,157,004, an improved burnishing apparatus using a U-shaped tub mounted on trunnions was disclosed wherein vibratory force was applied directly to the tub such that the force passed through its center of gravity. When the U-shaped tub was tilted about the trunnions, the vibratory force was used for the purpose of discharging the media and parts from the tub.
Although improved burnishing of the parts resulted from this use of vibratory motion in a tumbling apparatus, problems continued with the balance of the machine. These included wear on bearings and the time it took to obtain the desired finish. To overcome such problems, a vibrating tumbling apparatus was conceived and developed as more fully disclosed and claimed in my earlier U.S. Pat. No. Re. 33,542.
According to that invention, a container is vibrated along small segments of an arcuate or circular path centered at a point offset from the center of the container. The material in the container is moved or conveyed and tumbled not only due to the coefficient of friction of the material with the surface of the container, but also due to the angle of attack between the material and the surface of the container at any given point because of the segmental circular path. While highly satisfactory tumbling action resulted from this improved arrangement, certain problems were discovered which required still further attention to more closely perfect the device.
In particular, my earlier U.S. Pat. No. Re. 33,542 taught that the inner surface of the container may be coated or lined. More specifically, this coating or lining was taught as comprising a material having a particular coefficient of friction which typically would comprise a material such as rubber or leather, which material was to aid in the conveying action and to improve the tumbling of the parts. In addition, the liner on the inner surface of the container was recognized as comprising a wear surface which could be replaced when worn.
Unfortunately, typical materials utilized because of their coefficient of friction usually have certain less than desirable physical characteristics. For instance, rubber or leather which is otherwise well suited for the intended purpose cannot withstand high temperatures and, thus, hot castings cannot immediately be treated in such a vibratory tumbling apparatus without the liner incurring substantial damage. Furthermore, depending upon the materials treated in the apparatus, the useful life of the liner is less than would normally be considered desirable.
In addition, in order to maximize the mixing, burnishing, blending etc., it is desirable for the material in the apparatus to be able to experience the best possible tumbling action. Thus, when the vibratory tumbling apparatus utilizes a generally horizontally arranged cylindrical container, it is desirable for the material to be vibrated upwardly along the inside surface of the container to the maximum extent possible before the material falls back by gravity to a lower point in the container. However, while conveying action is enhanced by utilizing a carefully selected liner, e.g., rubber or leather, it remained desirable to be able to convey the material to a still higher point.
To achieve this purpose, my earlier U.S. Pat. No. 4,926,601 taught the material supporting surface as having a plurality of generally circumferential, parallel troughs. These troughs were more specifically taught as being disposed about and spaced along the generally horizontal longitudinal axis of the curved or arcuate material supporting surface. While conveying material to a higher point is successfully achieved, it would remain desirable to be able to enhance the tumbling action of the material within the container.
The present invention is specifically directed to overcoming one or more of the foregoing problems and accomplishing one or more of the resulting objectives in a novel and efficient manner.